Looking through a few things here, I came across something that may be of interest to a few of you. I have been shooting in competitions for around 45 years, and have amassed just a huge library of things that I have written, collected, been given, and observed. This thread has to do with "dope," not the stuff you smoke, the stuff that shooting long distance, can't be neglected, if you want to do it right.

Definition's:

Dope- The observed information about conditions that will cause affects on bullets in flight at a particular location at the present time.

Doping- The art of transposing observed information to the equipment you have at hand for the purpose of refining shot placement.

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The fact is, that it is not cut and dried. Doping is an art, something that is developed and acquired with the experience of shooting long range over a period of time. People involved in long range shooting have looked for ways of simplifying doping. Some easy formula that will work 100% of the time in any condition with an exactness that will place their shot in the middle of the target every time, on any given range. If this were available, I would simply put this formula at the end of this thread.

While this is a lesson in exterior ballistics, I want to move a little further along, with the belief that you already know the zeros for your rifle. We all know, that if we go back to the same range and have the same conditions, with the same gun, and same ammo, we can all duplicate the same shot placement as we did the time bbefore.

Lets just look at the variation of conditions possible between the rifle, the target, and the factors causing change in bullet impact. The factors are;

a. Temperature

b. Available light

c. Humidity

d. Elevation

e. Wind, it's Direction and Velocity

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Temperature:

A rise in temperature can increase velocity. Increased velocity will cause the impact of your round to be higher than your zero.

One minute of angle is equal to roughly 1 inch per every one hundred yards. An increase of 15 degrees in temperature will displace a round one minute high at 600 yds, and a ten degree change will cause one minute displacement at 1000 yds.

At shorter ranges, we may overlook this as it may not seem necessary, but think of this, if you are hunting in winter conditions, where you store your gear in your car or truck for traveling to your hunting spot, how hot or cold does it get? Common experience will tell you that you can expect as much as a 40 degree change from your car to the weather, and even more as some of you can testify.

If you use a thermometer when you practice, you should record temperatures in your log book and it is important to evaluate your conditions during practice AND when you get home. Have you ever wondered why you put on clicks in the morning and take them off in the afternoon? Change in temperature may have been the variable that you didn't take into consideration.

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Light:

The direction of light and it's intensity can change where the target appears to be. Iron sight shooters have  a hard and fast rule that they use; "un up, sights up, sun down, sights down."

When the sun is bright, a distortion will form around the target. This usually causes the shot to print low, the target appears to be higher than it is. When you have cloud cover, there is very little or no distortion. The tendency is to hold closer to where the target actually is, which will result in a higher than expected shot. The brighter the sun, the bigger the target will actually seem.

How much displacement depends on the brightness of the sun and the distance you are from the target. PRACTICE in variable conditions will increase your hit probability.

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I want to go into this further, but it's getting late and I am typing with my eyes propped open. I will be back with more tomorrow, pprobably. Getting tired for now....................Kingpin

Good thread, Kingpin. I also shoot long range competition, and doping is an important part of the game. I learned a long time ago with verier sights, morning to afternoon will change sight setting two points or so. One of the hardest things to learn is reading how mirage is running, which is a big bugaboo here on the high plateau, with strong sun and wind to contend with. I know on the Rocker range, the wind blows hard enough to take over the sillywette targets at times. Down at Lone Pine, the seventeen hundred fifty yard target at the last match took ALL the left windage, plus a bit of the ol 'Kaintuck thrown in for good measure to get on in the thirty to fourty mile winds. The guys who come from back east to shoot have the fits with this wind!

Light is a definite factor with aperture sights. A cloud coming over on a shot can have all kinds of nasty effects on me, as time is of the essence, once windage is dialed in. The top shooters tell me you have about seven seconds from the time of dialing in your windage to get your shot off in local conditions here, due, once again, to the changing winds. I listen when old Butch and Ted Tompkins talk, as both have several national championships for shutzen and BPCR rifles under thier belts, and I learn more from them every time I shoot with them.

Very good points kingpin and I hope you print some more.I think you should aim to learn something new everyday.Expierence is the greatest teacher.

Waksupi your area must be similar to mine for wind and mirage.I have given up the iron sights this year to concentrate on the scoped class.But when I was using them you click and shoot or you have to click again.

Macca

About 20 years ago I got lots of ballistic tables and started graphing my trajectories.  In 1981 I got my first PC and wrote some programs.  I always used range data as my inputs rather than theoretical stuff.

I agree that many things effect your bullet once it leaves the barrel and lots of stuff before it leaves the barrel.  But I've always neglected the effects of temperature, as they are FOR ME negligible.  Wind has always been my big problem in doping out a long shot, especially since I shoot in the east with lots of ridges and 'foothills'. 

Gusting and changing wind is 90% of my problem in long range shooting.  Like you say, it would be great if there was a quick rule of thumb that worked ever time.  Knowing your trajectory in 'zero wind conditions' is always my starting point.

But after all is said and done, I end up making a gut decision based upon past shooting experience and variations I observe.  Alway a gut hold over/off that I 'feel' is right. 

Last year I hunted Prairrie Dogs in N. Dakota with gusting winds to 35 MPH.  It was funny cause those 6mm pills were everywhere.  These plains winds were unusual conditions for me, but by the end of the first day, I was averaging closer misses with an occasional hit. 

Maybe it is like landing a plane.  You need to know all the technical stuff, but the dope is only learned by doing it lots?

Good topic KP.

BEAR

Thanks for the article KP.

This is something the long range wanna be's need to take into account - myself included.  I see WAYYY too many deer hunting types just buy into what some manufacturer's trajectory table says and go from there.  I suppose it's better than nothing but not by much.

The key to LR shooting/hunting is practice and lots of it IMHO.  Because it is such an investment, I only have 1 rifle for the LR stuff, my 7 RUM Sendero.  It has the mil-dot reticle and though I didn't get to do a lot of shooting with it last year, I've run the numbers and put in some more range time than I did last year.  I believe that if you have 1 good LR rifle then that's all you need b/c of the time and $$$ involved.

Good stuff KP, look forward to hearing more!

Elevation and humidity:

We all have to evaluate the effect of air density, which produces drag placed upon the bullet in flight. The higher the altitude, the thinner the air. Given a zero at a lesser altitude, your bulet will print higher when fired in the higher elevation. Humidity is simply the amount of moisture in the air. Moisture in the air places drag on the bullet. The more moisture, the more drag, which will cause your bullet to print lower.

How much displacement, depends on how much conditions have changed from those when zeroing, and as usual, how far you are from the target.

If are planning to hunt in a certain area, at different elevations, you SHOULD have zeros for each variation. As hunters, we don't normally do that and have to rely on the otiginal zeros. This doesn't make it roght, it just makes it seem like common sense.

Barometric pressure normally ranges in the area of 29.0 to 32.0 psi. Decreases in barometric pressure will decrease the density of the air, and allow the bullet to impact higher on the target.

The chart illustrates the approximate change of impact from sea level to ten thousand feet, given the rifle was zeroed to point of aim, point of impact at sea level. The chart is also dependant upon shooting match grade ammo in .308 Winchester caliber at approximately 2600 FPS.

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Impact Rise With Change Of Elevation In Minutes Of Angle

Range         & nbsp;      2500 ft         &nbs p; 5000 ft         &nbs p; 10,000 ft

100 yd         &nbs p;    .05         &nb sp;        .08                     .13

200 yd         &nbs p;    .1         &nbs p;         .2&n bsp;         &n bsp;         &n bsp;  .34

300 yd         &nbs p;    .2         &nbs p;         .4         &nbs p;         &nbs p;   .6

400 yd         &nbs p;   .4         &nbs p;         &nbs p;.5         &n bsp;         &n bsp;   .9

500 yd         &nbs p;  .5         &nbs p;         &nbs p; .9        &n bsp;         &n bsp;  1.4

600 yd         &nbs p;  .6         &nbs p;         &nbs p;1.0         & nbsp;         & nbsp;1.8

700 yd         1.0& nbsp;         & nbsp;         1 .6         &nbs p;          2.4

800 yd         1.3& nbsp;         & nbsp;        1.9         &nb sp;         &nb sp; 3.3

900 yd        1.6 & nbsp;         & nbsp;       2.8         &nb sp;         &nb sp;  6.0

1000 yd      1.8                   3.7         &nb sp;         &nb sp;  6.0

This info  has been computer generated, (so I was told) and generally reliable (which I have found that it is) It does NOT take the place of actual dope developed by a rifleman. I would suggest that you use this info for a reference only.

Wind Direction and its Velocity:

On the average, hunters kill game at 75 yards or less. Within this distance, wind effect on shot placement is very little. Lets move the target down range and talk about average shots. There are two reasons for this:

a. The potential is there to need a shot like this.

b. We all still have to hit where aiming.

It should be obvious that the distance from the target will dictate the amount of adjustment required to compensate for given conditions. This is true because the farther you are, the longer the bullet is in flight. The longer the bullet is in flight, the more time conditions have to influence its travel.

On ranges of known distance, the flag system is most often used to determine wind direction and velocity. Flags, or wind socks are placed on poles to be up range from the target. The shooter views the flags to determine direction. By calculating the angle of the flag and dividing by a number representing the caliber of the round being fired, the shooter can determine velocity. An explaination for this method can be found in most rifle data books. Lots of guys use this method, but I for one can't figure out why. I would think, like a wind reading instrument (anemometer), taking the flags into account with everything else, it provides the shooter with more info that can verify their decision. Here are the problems with flags:

a. Flags fly high above the berms, and the bullet doesn't. Generally the wind flag is NOT the condition that will effect the bullet in flight.

b. Looking at flags across a long range will generally give you conflicting info because wind conditions are seldom consistant over long distance.

c. Dpending on the weight of the flag, the material it's made of, orthe amount of moisture it has collected, the wibd will move it differently.

d. Flags do NOT respond quickly to change.

These are the main reasons why flags are not my choice. From a sshooters eye, whatever you can see moving between you and the target is more important. Make sure it's between you and the target. Don't be a victimof false indicator. Wind vanes on top of barns are no indicator of what the wind is doing at ground level. Look for things like, a flag attached to a house, clothes on a line, water rippling on the surface of a pond, blades of grass and things like that.

Keep in mind that wind moves differently around buildings. Your radio station may tell you that the wind is out of the west today. This is NOT an indication that this is the condition where you are. Sometimes, even wetting your finger and holding it up in the breeze is as good as you are going to get.

For the long shot, we have to hurry up, get into position, and then put yourself on hold to evaluate the conditions.  A dominanant condition is simply that condition that is visible for most of the time. Then you should look for variations in conditions. Check the mirage, with a spotting scope if you are carrying one. Check the wind at midrange, check the light, monitor your breathing. Excitement plays hell with heart rates.

Mirage is simply heat waves reflecting from an object. The warmer the day, the more mirage you will see. Distortion is what you look for in your scope. When you see these waves, movement will be seen also. The direction of the movement is the way that the wind is blowing at that specific time. Ideally, the bst place to read mirage is about halfway between you and the target, but ideal is not always available. You may have to improvise, at a different distance, look for anything in sunlight.

Be back in a little while. This typing is making my eyes cross. 

Kingpin.......Well stated facts sir!

Something a lot of younger hunters should take advantage of and learn to a certain degree before they attempt to take that big mulie buck standing at 450 yards.

The more you learn, the more you will know and that translates in to more hits on targets down range.